SNOWIN’ TO BEAT SNOWIN’ TO BEAT THE BANDTHE BAND

Using Satellite and Local Analysis and Prediction System Output to Diagnose the Rapid

Development of a Mesoscale Snow Band

Eleanor Vallier-Talbot and David R. Vallee

NOAA/NWS Taunton, MA

Fast Hitting SnowstormFast Hitting Snowstorm

Fast moving storm produced swath of 12-16 snows across major metro areas of Southern New England

MethodologyMethodology“Anticipating Mesoscale Band Formation”“Anticipating Mesoscale Band Formation”

WFO Taunton has incorporated the method outlined in Novak, D.R., 2002, for anticipating band formation.

Critical Elements:– Upper Level Divergence–Mid Level Frontogenesis/Instability– Snow Growth and CSI Potential

MethodologyMethodology“Anticipating Mesoscale Band Formation”“Anticipating Mesoscale Band Formation”

Day shift forecasters used the same approach incorporating an updated version of the Local Analysis and Prediction System Output (LAPS) in real time along with Satellite signatures.

Helped diagnose the northwest displacement and resulted in dramatically higher snowfall forecast.

Eta Model GuidanceEta Model Guidance

NWP/Eta Model was forecasting cyclogenesis along mid Atlantic coast

Low to pass well south and east of Cape Cod– A track far enough off shore which doesn’t

often produce heavy snows far inland

Eta Model GuidanceEta Model Guidance

Co-location and placement of upper level divergence, mid level frontogenesis and max upward motion and potential for efficient snow growth were poised to occur along or just off the coast of Southern New England

Composite 4-panel - 24 hr fcst valid 12 UTC 7 Feb 03Composite 4-panel - 24 hr fcst valid 12 UTC 7 Feb 03

Composite 4-panel - 30 hr fcst valid 18 UTC 7 Feb 03Composite 4-panel - 30 hr fcst valid 18 UTC 7 Feb 03

Composite 4-panel - 36 hr fcst valid 00 UTC 8 Feb 03Composite 4-panel - 36 hr fcst valid 00 UTC 8 Feb 03

Cross Section – 30 hr fcst valid 18 UTC 7 Feb 03Cross Section – 30 hr fcst valid 18 UTC 7 Feb 03Lebanon, NH to 150 nm south of Martha’s Vineyard, MALebanon, NH to 150 nm south of Martha’s Vineyard, MA

Time Height Cross Sections Time Height Cross Sections 12 UTC Run for Eta at Norwood, MA12 UTC Run for Eta at Norwood, MA

-8-8°C°C

-18-18°C°C

-12-12°C°C

-16-16°C°C

Time Height Cross Section Time Height Cross Section 12 UTC Run for Eta at Nantucket, MA12 UTC Run for Eta at Nantucket, MA

-8-8°°CC

-18-18°C°C

-12-12°C°C

-16-16°C°C

Composite 4-panel - 12 hr fcst, valid 12 UTC 7 Feb 03Composite 4-panel - 12 hr fcst, valid 12 UTC 7 Feb 03

Composite 4-panel - 18 hr fcst, valid 18 UTC 7 Feb 03Composite 4-panel - 18 hr fcst, valid 18 UTC 7 Feb 03

Composite 4-panel - 24 hr fcst, valid 00 UTC 8 Feb 03Composite 4-panel - 24 hr fcst, valid 00 UTC 8 Feb 03

Cross Section – 18 hr fcst valid 18 UTC 7 Feb 03Cross Section – 18 hr fcst valid 18 UTC 7 Feb 03Lebanon, NH to 150 nm south of Martha’s Vineyard, MALebanon, NH to 150 nm south of Martha’s Vineyard, MA

Time Height Cross Sections Time Height Cross Sections 00 UTC Run for Eta at Norwood, MA00 UTC Run for Eta at Norwood, MA

-18-18°C°C

-8-8°C°C

-16-16°C°C

-12-12°C°C

Time Height Cross Sections Time Height Cross Sections 00 UTC Run for Eta at Nantucket Island, MA00 UTC Run for Eta at Nantucket Island, MA

-18-18°C°C

-8-8°C°C

-16-16°C°C

-12-12°C°C

RUC40 Model GuidanceRUC40 Model Guidance

06Z Run of the Eta continued to present a similar solution to the 12z/6th and 00z/6th runs

Winter Weather Experience (WWE) collaborative efforts also placed axis of heaviest snows along the immediate south coast of New England

RUC40 guidance from the 09Z run began to at least hint at a northwest displacement to the major forcing mechanisms

Composite 4-panel – 09 UTC RUC40 Valid 12 UTC 7 Feb 03Composite 4-panel – 09 UTC RUC40 Valid 12 UTC 7 Feb 03

Composite 4-panel – 09Z RUC40 Valid 15 UTC 7 Feb 03Composite 4-panel – 09Z RUC40 Valid 15 UTC 7 Feb 03

Composite 4-panel – 09Z RUC40 Valid 18 UTC 7 Feb 03Composite 4-panel – 09Z RUC40 Valid 18 UTC 7 Feb 03

Reality Check….Reality Check….

Satellite and LocalLAPS Data tell the tale!

Major Corridor of very heavy snow did develop across the CWA

But did it occur along the south shore where we all thought it would?????

Water Vapor ImageWater Vapor Image06 UTC, 7 Feb 0306 UTC, 7 Feb 03

Water Vapor ImageWater Vapor Image12 UTC, 7 Feb 0312 UTC, 7 Feb 03

Composite 4-panel - LocalLAPS Valid 12 UTC 7 Feb 03Composite 4-panel - LocalLAPS Valid 12 UTC 7 Feb 03Frontogenesis is displaced to the northwest!Frontogenesis is displaced to the northwest!

Composite 4-panel - LocalLAPS Valid 16 UTC 7 Feb 03Composite 4-panel - LocalLAPS Valid 16 UTC 7 Feb 03Corridor moving right across the CWA!Corridor moving right across the CWA!

16Z Visible Image16Z Visible ImageNote the “Convective” look to the cloud pattern!Note the “Convective” look to the cloud pattern!

WSR-88D Base ReflectivityWSR-88D Base Reflectivity

WFO BOX

Valid Time:

14 UTC through 17 UTC

Visible Satellite Loop Visible Satellite Loop

Valid Time:

14 UTC through 20 UTC

18Z Visible Image18Z Visible ImageNote the “Convective” look to the cloud pattern!Note the “Convective” look to the cloud pattern!

Water Vapor ImageWater Vapor Image18Z, 7 Feb 0318Z, 7 Feb 03

Composite 4-panel – LocalLAPS Valid 18 UTC 7 Feb 03Composite 4-panel – LocalLAPS Valid 18 UTC 7 Feb 03Corridor moving right across the CWA!Corridor moving right across the CWA!

LAPS Cross Section valid 16 UTC 7 Feb 03LAPS Cross Section valid 16 UTC 7 Feb 03Lebanon, NH to 150 nm south of Martha’s Vineyard, MALebanon, NH to 150 nm south of Martha’s Vineyard, MA

LAPS Time Height over Norwood, MALAPS Time Height over Norwood, MAAgain…quite productive!Again…quite productive!

-18-18°C°C

-8-8°C°C

-16-16°C°C

-12-12°C°C

18 UTC Base Reflectivity and Surface Weather, Ceiling and Visilbiites18 UTC Base Reflectivity and Surface Weather, Ceiling and VisilbiitesVsby ¼ to ½ mile in moderate/heavy snowVsby ¼ to ½ mile in moderate/heavy snow

Observed Snowfall Analysis - February 7th, 2003 Snowstorm

WFO Taunton PerformanceWFO Taunton Performance

WFO Taunton lead times:– 45 hours on Outlook Statement– 36 hours for the watch– 24 hours for warning South Coast, Cape

Cod and the Islands But: very short lead time Providence to

Boston Metro Corridor!– Just 1 to 4 hours!

Using Satellite and LAPS Data to Diagnose the Using Satellite and LAPS Data to Diagnose the Evolution of a Heavy Snow BandEvolution of a Heavy Snow Band

Appreciate your time!

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